A new assessment by U.S. intelligence officials reportedly says North Korea has produced a miniaturized nuclear warhead that can fit inside intercontinental ballistic missiles, a development that led to a fiery rebuke from President Donald Trump.

The confidential analysis says "the IC [intelligence community] assesses North Korea has produced nuclear weapons for ballistic missile delivery, to include delivery by ICBM-class missiles,” according to an excerpt The Washington Post says was read to it. Two officials familiar with the document, which was completed last month, verified the contents to the Post.

Trump, meanwhile, said North Korean leader Kim Jong Un has been "very threatening beyond a normal statement" and vowed strong repercussions if the nuclear threat continues.

"They will be met with fire, fury and, frankly, power, the likes of which this world has never seen before," the president said at a briefing on opioid addiction at his golf course in Bedminster, N.J.

North Korea's military is "examining the operational plan" to strike areas around Guam with medium-to-long-range strategic ballistic missiles, state-run news agency KCNA said early Wednesday local time.

The threat comes just hours after US President Donald Trump warned Pyongyang that if they continued to threaten the US, they would "face fire and fury like the world has never seen."

The Defense Intelligence Agency and Office of the Director of National Intelligence declined to comment on the report, but the analysis matches a Japanese defense assessment this week that said it is possible North Korea has achieved the difficult task of miniaturization. North Korea claimed to have tested the smaller design last year, but that has not been confirmed.

The findings would put North Korea's nuclear program years ahead of projections, according to some analysts, and bring it closer to its long-sought goal of becoming a nuclear power that can strike the U.S..

Officials have calculated that Kim Jong Un controls as many as 60 nuclear weapons, but other experts believe the number is far lower. North Korea has conducted five nuclear tests since 2006, with the most recent occurring Sept. 9, 2016.

"What initially looked like a slow-motion Cuban missile crisis is now looking more like the Manhattan Project, just barreling along," said Robert Litwak, a nonproliferation expert at the Woodrow Wilson International Center for Scholars told the Post. "There’s a sense of urgency behind the program that is new to the Kim Jong Un era."

North Korea has tested ICBMs in recent weeks, though a video analysis of a launch last month showed the missile caught fire on reentry. The test drew a new set of harsh economic sanctions from the U.N. Security Council over the weekend.

The nation's state-run news agency responded that "(North Korea) will make the U.S. pay dearly for all the heinous crimes it commits against the state and people of this country."

Speaking at the ASEAN Regional Forum on Monday, North Korean Foreign Minister Ri Yong Ho blamed the U.S. for the current situation on the Korean Peninsula and said Pyongyang's "possession of nuclear weapons and intercontinental ballistic missiles is a legitimate option for self-defense in the face of a clear and real nuclear threat posed by the US," according to a statement.

Trump's national security adviser, H.R. McMaster, said over the weekend that "all options" are on the table to deal with North Korea.

Trump tweeted early Tuesday "After many years of failure, countries are coming together to finally address the dangers posed by North Korea. We must be tough & decisive!"

After many years of failure,countries are coming together to finally address the dangers posed by North Korea. We must be tough & decisive!